WO1996040568A1

WO1996040568A1 - Screw cap made of moulded synthetic resin with sealing lip for axial leaktightness

Info

Publication number: WO1996040568A1
Application number: PCT/IT1996/000113
Authority: WO
Inventors: Bruno Taddei
Original assignee: Bruno Taddei
Priority date: 1995-06-07
Filing date: 1996-06-03
Publication date: 1996-12-19
Also published as: AU5910396A; ITFI950129A0; IT1278697B1; ITFI950129A1

Abstract

In order to form a frontal seal between the top (1A) of the cap (1) and the terminal edge (C2) of the bottle neck (C), a lip (9) in the form of a discoid sheet diaphragm is provided, originating from the central area (1C) of said end (1A) and extending slightly away from it, said discoid lip (9) being deformed by the terminal edge (C2) of the neck when the cap has been screwed on to the neck, until it is made to ride over an internal edge (1E).

Description

Screw Cap Made of Moulded Synthetic Resin with Sealing Lip for Axial Leaktightness

Technical Field

The invention relates to an effective and easily implemented solution for ensuring the leaktightness of a cap applied to a container for mineral water and other beverages and for equivalent uses, even when there are imprecisions in the dimensions of the neck of the container, which is usually produced by- blow moulding.

Summary of the Invention

According to the invention, the screw cap. made of moulded synthetic resin, for glass or blow- moulded plastic bottles having their necks provided with a male thread or an equivalent system of application, comprises, as the seal between the cap and the terminal edge of the bottle neck, a lip originating on the inside of the top of the cap, extending symmetrically about the geometrical axis of the cap, and capable of interacting with said terminal edge of the neck when the cap has been screwed on to the neck.

In a possible embodiment, the cap comprises, as the frontal seal between the top of the cap and the terminal edge of the bottle neck, a lip in the form of a discoid sheet diaphragm originating from the central area of said top and extending slightly away from it, which discoid lip is deformed by said terminal edge of the neck when the cap has been screwed on to the neck.

An inner edge may be provided adjacently to the top of the cap, the periphery of said discoid lip bearing on this edge and the lip being deformed at the periphery in such a way as to force it on to the terminal edge of the neck. In another possible embodiment, the cap com¬ prises, as the seal between the cap and the terminal edge of the bottle neck, a lip which extends substantially in the form of a truncated cone originating from and extending away from the top of the cap and which is bent back toward the periphery of the top so that it interacts with the internal surface of the top and with the terminal frontal surface of the terminal edge of the bottle neck, when the cap has been screwed on to the neck. Said lip extending in the form of a truncated cone is at least partially deformed and bent back toward the top of the cap before application.

The invention also relates to a means for the production of the cap described above, being a mould which comprises a female part, a core and an intermediate component, which together with the female part forms the cap and together with the core forms the lip.

Brief description of the drawings

The invention will be more clearly understood from the description and the attached drawing which shows a non-restrictive practical example of the invention. In the drawing, Fig. 1 shows an embodiment of the cap according to the invention in a section through a diametric plane, in the conditions preceding application;

Fig. 2 shows the application of the cap to a bottle neck, in the conventional embodiment and with the seal according to the invention between the end of the bottle neck and the cap;

Fig. 3 shows a detail illustrating the shape of a mould for making the end seal of the cap on the bottle neck or on another item;

Figs. 4 and 5 show another embodiment of the cap, in the form in which it leaves the mould and in its final form; Figs. 6, 7 and 8 show a closed mould with the cap formed in it, and in two successive configurations for the extraction of the finished piece;

Figs. 9 to 12 show a device for the deformation of the lip forming the seal, to be used after moulding; and

Figs. 13, 14 and 15 show a device modified from that shown in Figs. 9 to 12.

Detailed description of the invention

According to the illustrations in Figs. 1 and 2 of the attached drawing, the number 1 indicates in a general way the cap which comprises a top wall 1A and a lateral wall IB which is circular and usually made with an internal thread indicated in a general way by 3. In conventional solutions, a collar 5, shaped externally to interact with the internal wall Cl of the neck C of the bottle or flask to which the cap is applied, is provided on the inside of the top 1A of the cap (see Fig. 2, right). The internal diameter, in other words the diameter of the internal surface Cl of the neck C of the bottle (made of glass or made of thermoplastic material by blow moulding) is never quite accurate, and consequently the seal provided by this collar 5 is not satisfactory, particularly when there is pressure inside the bottle, for example an aerated beverage.

According to the illustration in Figs. 1 and 2 (and only on the left-hand side of Fig. 2), the internal collar 5 illustrated in the right-hand part of the section in Fig. 2 is replaced by a lip in the form of a discoid sheet diaphragm indicated by 9 in the drawing, which is moulded simultaneously with the cap, in a mould, for example, of the type indicated in Fig. 3. This diaphragm lip 9 originates from a central core 1C of the top 1A, inside the cap; the periphery, in other words the terminal edge 9A of the said discoid diaphragm lip 9, is designed to interact with a small internal edge IE originating from the wall IB of the cap 1 near the top 1A of the cap. The discoid diaphragm lip 9 extends in the form of a truncated cone with a very large aperture, for the purposes stated below. For the moulding, the use of a three-component mould as shown in Fig. 3 is envisaged, with a female part SI, an internal core S2, and an intermediate component S3 which is slidable and can be connected slidably to the core S2, the said intermediate component S3 extending so that it forms the internal part of the wall IB with the thread 3 and also delimits - by means of an inward extension S3A - the area of separation between the top 1A and the discoid diaphragm lip 9, in combination with the terminal surface S2A of the core S2 extending in the form of a truncated cone matching an opposing surface of the internal extension S3A. It is clear that the core S2 can be withdrawn axially from the female_. part SI, while the intermediate component S3 can be unscrewed from the moulded threaded part or can be extracted independently by a rotation, while the injected material is still hot, an axial relative separation of the intermediate component S3 and the core S2 then being carried out to release the discoid diaphragm lip 9 of the cap.

The peripheral edge 9A of the discoid diaphragm lip 9 is capable of interacting with the edge IE, which is contiguous to the top 1A and is inside the cap, when the cap is screwed on to the bottle neck C. In these conditions, the terminal edge C2 of the bottle neck C comes into contact with the peripheral area of the discoid diaphragm lip 9 and causes its deformation as may be seen in the left-hand part of Fig. 2; when the cap has been screwed on, the peripheral part 9A of the discoid diaphragm lip 9 rides over the edge IE and definitively deforms the discoid diaphragm lip 9 into a curve such that a frontal contact pressure of this lip 9 on the end C2 of the bottle neck C is produced. In this way the seal is ensured and is frontal instead of being internal with respect to the edge Cl as in the case of a conventional internal projection 5 (visible in the right-hand part of Fig. 2), which, as has been stated, is not satis actory, owing to the possible imprecision of the diameter of the surface 5 of the neck of the bottle.

According to Figs. 4 and 5, in which the same references are used for elements corresponding to those in the version shown in Figs. 1 and 2, the virtually discoid lip 9 is replaced by a lip 19 (Fig. 4) extending substantially in the form of a truncated cone, originating and expanding from the central area 1C of the top 1A. Said lip 19 extending substantially in the form of a truncated cone is relatively very thin and can be deformed after moulding by a supplementary operation which can be carried out in the hot or cold state; the lip 19 shown in Fig. 4 can be deformed into the configuration indicated by 19X as illustrated on the left-hand side of Fig. 5, so that it becomes wedged under the edge IE. When the cap 1 is screwed on to the bottle neck C, the lip 19 can be deformed again from the configuration 19X to the configuration 19Y as illustrated on the right-hand side of Fig. 2, and provides the seal both frontally, between the terminal edge C2 of the neck C and the top 1A, and also partially inside the neck C adjacently to the terminal edge C2.

To produce the cap according to the embodiment shown in Figs. 4 and 5, the device shown in Fig. 6 and the following figures may be provided. Said device comprises (Figs. 6, 7 and 8) a mould having three parts, namely a female part Sll, a core S12 with a truncated conical terminal profile S12A, and an intermediate component S13 having an extension S13A. Two ejectors S14 and S15 are used to facilitate the extraction of the moulded cap in the shape shown in Fig. 4. After injection moulding (see the configuration shown in Fig. 6), the female part Sll and the core S12 are moved axially with respect to the cap 1 in opposite directions (see the configuration shown in Fig. 7); the extraction of the piece 1 is then completed by the operation of the ejectors S14 and S15 (Fig. 8).

To deform the lip 19 from the shape shown in Figs. 4, 6, 7 and 8 to that shown on the left-hand side of Fig. 5, the device shown in Figs. 9 to 12 may be used. Said device comprises an internal member 21 which is slidable inside an external member 23 and is forced by a spring 25 to bear on an internal stop 23A of said member 23. The working ends of the two members 21 and

23 are shaped with approximately truncated conical profiles, one convex (2IX) and one concave (23X) , which act in succession on the lip 19 causing its deformation from the configuration shown in Fig. 9 to that shown in Fig. 12.

Figs. 13 to 15 show a variant of Figs. 9 to 12. In this variant, the external member 33 (equivalent to 23) which surrounds the internal member 31 (equivalent to 21) has a convex truncated conical profile 33X, forming an extension of the truncated conical profile 31X, and a flat portion 33Y. In this case also, the lip 19 is deformed until it curves under the edge IE.

The edge IE ensures the retention of the lip 19, against the tendency of said lip to partially return from the configuration 19Y to the initial configuration 19.

The device shown in Figs. 9 to 12 or Figs. 13 to 15 may be multiple, to act on multiple seats Tl of a belt T which feeds the caps 1 forward in the said seats

Tl, so that the devices 21, 23 or 31, 33 act against a support A.

The cap 1 will be provided with suitable means which form a seal capable of ensuring protection against unauthorized opening of the container.

It is to be understood that the drawing shows only an example provided solely as a practical demonstration of the invention, and that this invention may be varied in its forms and dispositions without departure from the scope of the guiding concept of the invention.

Claims

1. Cap made of moulded synthetic resin, for glass or blow-moulded plastic bottles having their necks (C) provided with a male thread (C5) or an equivalent system of application, characterized in that it comprises, as the seal between the cap (1) and the terminal edge (C2) of the bottle neck (C), a lip (9; 19) originating on the inside of the top (1A) of the cap, extending symmetrically about the geometrical axis of the cap, and capable of interacting with said terminal edge (C2) of the neck (C) when the cap has been screwed on to the neck.

2. Cap made of moulded synthetic resin, for glass or blow-moulded plastic bottles having their necks (C) provided with a male thread (C5) or an equivalent system of application, according to Claim 1, characterized in that it comprises, as the seal between the top (1A) of the cap (1) and the terminal edge (C2) of the bottle neck (C) , a lip (9) in the form of a discoid sheet diaphragm originating from the central area (1C) of said top ( 1A) and extending slightly away from it, which discoid lip (9) is deformed by said ter¬ minal edge (C2) of the neck when the cap has been screwed on to the neck.

3. Cap made of moulded synthetic resin, for glass or blow-moulded plastic bottles having their necks (C) provided with a male thread (C5) or an equivalent system of application, according to Claim 1, characterized in that it comprises, as the seal between the cap (1) and the terminal edge (C2) of the bottle neck (C) , a lip (19) which extends substantially in the form of a truncated cone originating from and extending away from the top of the cap (1) and which is bent back toward the periphery of the top (1A) so that it interacts with the internal surface and with the terminal frontal surface of the terminal edge (C2) of the bottle neck (C) , when the cap has been screwed on to the neck.

4. Cap according to Claim 1 or 2 or 3, characterized in that an inner edge (l£) is provided adjacently to the top (1A) of the cap (1), the periphery (9A; 19A) of said discoid lip (9; 19) bearing on this edge and the lip being deformed in such a way as to force it on to the terminal edge (C2) of the neck.

5. Cap according to at least Claim 3, characterized in that said lip (19) extending in the form of a truncated cone is at least partially deformed and bent back toward the top of the cap before application.

6. Device for producing the cap according to Claim 2 or 3, comprising a mould having a female part (SI; Sll), a core (S2, S2A; S12, S12A) and an intermediate component (S3, S3A; S13, S13A) which together with the female part (SI; Sll) forms the cap and together with the core (S2; S12) forms said lip (9; 19).

7. Device according to Claim 6, characterized in that is comprises a supplementary element with two members (21, 23; 31, 33) having shaped end profiles (21X, 23X; 31X, 33X, 33Y) capable of passing into the moulded cap to deform the lip (19) extending substantially in the form of a truncated cone to bend it back toward the top of the cap.